Explicit Network Scheduling

Richard John Black, Richard Black

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This dissertation considers various problems associated with the scheduling and network I/O organisation found in conventional operating systems for effective support for multimedia applications which require Quality of Service.

A solution for these problems is proposed in a micro-kernel structure. The pivotal features of the proposed design are that the processing of device interrupts is performed by user-space processes which are scheduled by the system like any other, that events are used for both inter- and intra-process synchronisation, and the use of a specially developed high performance I/O buffer management system.

An evaluation of an experimental implementation is included. In addition to solving the scheduling and networking problems addressed, the prototype is shown to out-perform the Wanda system (a locally developed micro-kernel) on the same platform.

This dissertation concludes that it is possible to construct an operating system where the kernel provides only the fundamental job of fine grain sharing of the CPU between processes, and hence synchronisation between those processes. This enables processes to perform task specific optimisations; as a result system performance is enhanced, both with respect to throughput and the meeting of soft real-time guarantees.